a. Field of the Invention
The present invention relates to the field of wiper extrusions, and more particularly relates to the field of dual wiper refill type extrusions. This invention relates to an improved extrusion the shape of which is less inclined to stress concentration related fractures and is a generally more compact and stiff extrusion.
b. Description of the Prior Art
The prior art includes several dual edge wiper extrusion pieces. The extrusion is usually combined with two or more squeegee wiping elements and further includes a brush or other type of surface clearing implement. A recently available prior art dual edge wiper extrusion is disclosed in U.S. Pat. No. D 304,709 to Sussich, shown in FIG. 6 herein. This wiper extrusion 40 is characterized by a squared off profile for the respective squeegee holding channels 42. Each channel 42 includes a right angle extension member 46 for attaching the extrusion to wiper assembly support elements. Each of the separate channels 42 and extension members 46 are attached one to the other by a bridging piece 44 extending between the channels along an upper edge of the extrusion. The location of the bridging piece 44 creates a full height channel 47 between the respective elements 42
Owing to the generally right angled profile of the Sussich extrusion and the edge positioned location of the bridging member 44, bending and flexing stresses induced during the mounting sequence to place the extrusion on a wiper assembly, i.e., trimming the extrusion to length and manipulating the extrusion to insert the end into successive wiper assembly supports, can cause the extrusion to crack along one or the other side of the bridging piece 44. Such cracking renders the extrusion useless since it no longer fits tightly within the wiper support arms and the squeegee holding elements 42 become separate articles.
Accordingly the extrusion according to the present invention eliminates the stress concentrations of prior art right angled extrusion, and relocates the bridging piece between the squeegee support channels to a central position between the channels creating a stiffer and more compact extrusion profile.